Looking for cheap summer DHW options

[mpilihp]

So I upgraded our small conventional wood boiler that had a 50 gal water jacket to a larger one with I think 130 gal water jacket.

I have an indirect DHW tank and have burned wood year round to heat it and my hot tub. Issue is now the new wood boiler takes a lot more wood to get up to temp and it generates a lot more radiant heat so I would prefer not to use it in the peak of summer.

With that I am looking at alternatives, I was looking at an on demand electric heater but several people have recommended they do not generate enough heat. I only want to use one shower at a time or one sink at a time and I have a water saver head on it so I would think it could handle it.

I have two open breaker slots in my panel so I could do a 18KW unit that has two 40 amp 240v heaters in it. Anyone have experience with this?

Space is an issue, my other thought is a small 10-12 gallon electric tank. I think with 12 gallons we could take two showers but not sure with 10. I measured and between the two of us we run the shower for 9-10 minutes each morning total. If I could find one with a 4500 watt 240v heater Im sure it would recover quick enough for the second person but all I am seeing are 1500 watt 120 volt units.

So looking for feedback on either option or a source for a 240 volt high watt small tank. Id prefer the tank as it would save a breaker slot in my panel.

Thanks

~ Phil

 

[maple1]

An ordinary electric tank heater. Size to suit (not sure how much space you have - I would put in a 40 but that is situation dependant). I would also get it up off the ground on a stand with insulation under the tank, cover/wrap it with another layer of insulation, and plumb in a heat trap at the tank exit. That's what I did with our 80 gallon unit. DHW in summer with that runs us about $25/mo, @ 0.18/kwh. Usually 4 of us here.

 

[mpilihp]

Hi thanks, Im going to avoid the on demand as there just too many mixed reviews on them and go with a small electric. My thought is put a heat exchanger on it as well so it too stays hot when I run the wood boiler in the winter.

Thanks ~ Phil

 

[Chris Hoskin]

given your needs, a tankless electric would work great. I don't think a 10 gallon electric will do the job for you and for the cost difference (almost none) I would recommend a standard 40 gallon electric. The nice thing about the 40 gallon electric is that it would be easy to plumb in between your indirect and the faucets/showers. So, if you are running the wood boiler, the indirect will send hot water to the electric and the elements won't come on except to make up for a little bit of standby loss. The tankless won't do that quite as well. The other option to consider is a heat pump water heater - very efficient, cools/dehumidifies the basement a bit and a good rebate available from Efficiency Maine, IRRC. You could also set that up like the 40 gallon electric.

 

[NateB]

I think I am missing something. Are you asking for a water heater for 2 people to take showers, or a water heater for 2 people to take showers and heat your hot tub?

If you just want enough for 2 people to take showers, I would recommend a Heat Pump Water Heater (HPWH). You get a cooled dehumidified basement and hot showers. What size is your indirect tank? I would guess the cost to be around $400 to be up and running. This solution will not work to heat your hot tub.

 

[mpilihp]

Hi thanks, so we are efficient showers, during the summer we take military showers to make the indirect DHW tank last several days which is heated by the wood boiler. I also checked our times in the shower and together its 10-12 mins. Our shower head uses 1 gallon a min (checked it) so 10 gallons in the tank will do us each day considering we mix in some cold.

If there is more hot water than you need you will use it, if you only have so much you will make it work right?? Less we use the lower our living costs will be.

On the rare occasions we have guests I can turn a dial and on demand heat our indirect DHW tank with the oil boiler or I can always just fire up the wood boiler as well.

Thanks

~ Phil